Chevron platform turbine vane

ABSTRACT

Gas turbine vanes of a gas turbine vane assembly have a reconfigured platform shape so as to reduce the ingestion of hot combustion gases into platform gaps between adjacent vane assemblies is disclosed. The vane platforms are configured so the joint between adjacent vanes is repositioned a sufficient distance away from the leading edge of the vane airfoil and the associated bow wave generated by the hot combustion gases passing over the airfoil leading edge.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

TECHNICAL FIELD

The present invention relates to gas turbine engines. More particularly,embodiments of the present invention relate to a gas turbine vane havinga platform shaped in order to reduce ingestion of hot combustion gasesinto joints between adjacent vanes of a vane assembly.

BACKGROUND OF THE INVENTION

A gas turbine engine operates to produce mechanical work or thrust. Fora land-based gas turbine engine, a generator is typically coupled to theengine through an axial shaft, such that the mechanical work of theengine is harnessed to generate electricity. A typical gas turbineengine comprises a compressor, at least one combustor, and a turbine,with the compressor and turbine coupled together through the axialshaft. In operation, as air passes through multiple stages ofaxially-spaced rotating blades and stationary vanes of the compressor,its pressure increases. The compressed air is then mixed with fuel inthe combustion section, which can comprise one or more combustionchambers. The fuel-air mixture is ignited in the combustion chamber(s),producing hot combustion gases, which pass into the turbine causing theturbine to rotate. The turning of the shaft also drives the generator.

A prior art turbine vane 100 is shown in FIG. 1. The turbine vane 100includes an inner platform 102, an outer platform 104 spaced a distanceradially outward relative to an engine centerline. Positioned betweenand connected to the platforms 102 and 104 is at least one airfoil 106.In operation hot combustion gases pass through the channels createdbetween the airfoils 106.

The turbine comprises a plurality of rotating and stationary stages ofairfoils. For the turbine vanes, the leading edge region of the airfoiland vane platform is subjected to the aerodynamic loads from thepreceding stage of turbine blades or the exit flow of a combustor. Thecombustion gases then pass around the airfoil, beginning at theairfoil's leading edge. Depending on the shape of the airfoil and theangle at which the flow of hot gases are imparted onto the leading edgeof the airfoil, a bow wave can be created, which is an area of highpressure combustion gases extending a distance away from the airfoilleading edge. This wave of combustion gases is often forced into theregion between adjacent turbine vanes in a vane assembly. Depending onthe supply pressure of the cooling air within the platform region andthe strength of the bow wave, the hot combustion gases of the bow wavemay penetrate into the joint between adjacent vanes, causing overheatingand erosion of the platform.

SUMMARY

Embodiments of the present invention are directed towards gas turbinevanes and a gas turbine vane assembly. In an embodiment of the presentinvention, a gas turbine vane comprises an inner arc-shaped platform, anouter arc-shaped platform, and an airfoil extending therebetween. Theinner arc-shaped platform has a pressure side radial face and a suctionside radial face where the pressure side radial face is formed in twointersecting portions and includes a relief cut at the intersection ofthe two portions. The outer arc-shaped platform, which is spaced aradial distance from the inner platform also has a pressure side radialface and suction side radial face where the pressure side radial face isalso formed having two intersecting portions and includes a relief cutat the intersection of the two portions. The outer arc-shaped platformis separated from the inner arc-shaped platform by at least one airfoil.The suction side radial faces each have a generally planar wall.

In an alternate embodiment of the present invention, a gas turbine vanecomprises an inner arc-shaped platform, an outer arc-shaped platform,and an airfoil extending between. The inner arc-shaped platform has apressure side radial face and a suction side radial face where thesuction side radial face is formed in two intersecting portions. Theouter arc-shaped platform, which is spaced a radial distance from theinner platform also has a pressure side radial face and suction sideradial face where the suction side radial face is also formed in twointersecting portions. The outer arc-shaped platform is spaced radiallyfrom the inner arc-shaped platform by at least one airfoil.

In yet another alternate embodiment of the present invention a gasturbine vane assembly is disclosed comprising a first vane assembly, asecond vane assembly, and a fastener mechanism. The first vane assemblyhas a first inner platform with a pressure side radial face having afirst portion and a second portion, a first outer platform with apressure side radial face also having a first portion and secondportion, and a first airfoil extending between the first inner platformand first outer platform. The second vane assembly has a second innerplatform with a suction side radial face having a first portion and asecond portion, a second outer platform with a suction side radial facealso having a first portion and second portion. The first vane assemblyand second vane assembly are fastened together along the surfacesopposite of the multi-surface platform faces by a fastener mechanism.

Additional advantages and features of the present invention will be setforth in part in a description which follows, and in part will becomeapparent to those skilled in the art upon examination of the following,or may be learned from practice of the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The present invention is described in detail below with reference to theattached drawing figures, wherein:

FIG. 1 depicts a perspective view of a gas turbine vane assembly of theprior art;

FIG. 2 depicts a perspective view of a gas turbine vane assembly inaccordance with an embodiment of the present invention;

FIG. 3 depicts a perspective view of the inner platform of the gasturbine vane assembly of FIG. 2 in accordance with an embodiment of thepresent invention;

FIG. 4 depicts a perspective view of components forming a gas turbinevane assembly in accordance with an embodiment of the present invention;

FIG. 5 depicts a perspective view of the outer platforms of a gasturbine vane assembly in accordance with an embodiment of the presentinvention;

FIG. 6 depicts a top view of a gas turbine vane assembly in accordancewith an embodiment of the present invention;

FIG. 7 depicts a graph of the gap pressure between the inner platformsof vanes of a gas turbine vane assembly of the prior art and anembodiment of the present invention;

FIG. 8 depicts a graph of the gap pressure between the outer platformsof vanes of a gas turbine vane assembly of the prior art and anembodiment of the present invention; and

FIG. 9 depicts a cross section view through a portion of the turbinevane assembly of the prior art within a turbine section showing thepressure isolines across the axial length of the turbine vane assembly.

DETAILED DESCRIPTION

The subject matter of the present invention is described withspecificity herein to meet statutory requirements. However, thedescription itself is not intended to limit the scope of this patent.Rather, the inventors have contemplated that the claimed subject mattermight also be embodied in other ways, to include different components,combinations of components, steps, or combinations of steps similar tothe ones described in this document, in conjunction with other presentor future technologies.

A gas turbine vane assembly 200 in accordance with an embodiment of thepresent invention is depicted in FIGS. 2-6. Referring to FIG. 2, the gasturbine vane assembly 200 comprises an inner arc-shaped platform 202having a pressure side radial face 204 and a suction side radial face206. The pressure side radial face comprises a first portion 204A, asecond portion 204B, and a relief cut 208 located at the intersection ofthe first portion 204A and the second portion 204B.

The gas turbine vane assembly 200 further comprises an outer arc-shapedplatform 210 spaced a distance radially outward of the inner arc-shapedplatform 202. The outer arc-shaped platform 210 has a pressure sideradial face 212 and a suction side radial face 214. The pressure sideradial face 212 comprises a first portion 212A, a second portion 212Band a relief cut 216 at the intersection of the first portion 212A andsecond portion 212B. The gas turbine vane assembly 200 also comprises atleast one airfoil 218 extending between the inner arc-shaped platform202 and the outer arc-shaped platform 210. Although a variety ofmanufacturing techniques can be used, for ease of manufacturing andstructural integrity, it is preferred that the inner arc-shapedplatform, airfoil, and outer arc-shaped platform are integrally casttogether.

The first portion 204A of the inner arc-shaped platform 202 is generallyco-planar with the first portion 212A of the outer arc-shaped platform210. Further, the second portion 204B of the inner arc-shaped platform202 is also generally co-planar with the second portion 212B of theouter arc-shaped platform 210. Alignment of these surfaces is necessaryto aid in assembly of the gas turbine vane assembly 200, as discussedbelow.

When the gas turbine vanes are assembled together in the turbine alongtheir corresponding chevron portions, it is necessary to place one ormore seals between adjacent platforms of the turbine vanes in order toprevent leakage between adjacent vanes. Referring again to FIG. 2, in anembodiment of the present invention, the first portion 204A and thesecond portion 204B of the inner arc-shaped platform 204 furthercomprises an inner seal slot 220. In this embodiment, the first portion212A and second portion 212B of the outer platform 210 also comprises anouter seal slot 222. Therefore, one or more seals (not shown) can beplaced in the slots 220 and 222 to seal the pressure side of the innerand outer platforms against an adjacent turbine vane. A variety of sealmaterials can be used, but one such material is a sheet metal seal, suchas that disclosed in U.S. Pat. No. 7,334,800.

Because of the extreme operating temperatures to which the turbine vane200 is exposed, it is often necessary to provide additional measures tohelp protect the turbine vane. Therefore, an embodiment of the inventionincludes applying a thermal barrier coating to the gas path surfaces ofthe inner arc-shaped platform, the outer arc-shaped platform, and atleast one airfoil. Also, in an embodiment of the invention, the vaneassembly may be actively cooled by directing an air source to theairfoil 218 through the outer arc-shaped platform 210.

Referring to FIGS. 2, 3, and 5, an alternate embodiment of the presentinvention is depicted. In the alternate embodiment, a gas turbine vane400 comprises an inner arc-shaped platform 402 having a pressure sideradial face 404 and a suction side radial face 406, where the suctionside radial face has a first portion 406A and a second portion 406B. Thegas turbine vane 400 also comprises an outer arc-shaped platform 408spaced a distance radially outward of the inner arc-shaped platform 402.The outer arc-shaped platform 408 has a pressure side radial face 410and a suction side radial face 412 where the suction side radial face412 comprises a first portion 412A and a second portion 412B. At leastone airfoil 414 extends between the inner arc-shaped platform 402 andthe outer arc-shaped platform 408. The inner arc-shaped platform 402,outer arc-shaped platform 408, and airfoil 414 are preferably integrallycast together.

The first portion 406A of the inner arc-shaped platform 402 is generallyco-planar with the first portion 412A of the outer arc-shaped platform408. While the second portion 406B of the inner arc-shaped platform 402is generally parallel to the second portion 412B of the outer arc-shapedplatform 408. Furthermore, the first portion 406A and the second portion406B of the inner arc-shaped platform 402 further comprises an innerseal slot 416. Also, the first portion 412A and second portion 412B ofthe outer arc-shaped platform 412 further comprises an outer seal slot418. Similar to the first vane assembly 200, one or more sheet metalseals can be placed in slots 416 and 418 to reduce leakage along theplatform sidefaces between the first and second portions of adjacentradial faces.

The gas turbine vane 400 also includes one or more alternatives forimproving the thermal capability of the vane. One such alternative is abond coating and thermal barrier coating. The bond coating and thermalbarrier coating is applied to a portion of the inner arc-shapedplatform, a portion of the outer arc-shaped platform and the at leastone airfoil extending between the platforms. An additional way ofimproving thermal capability is through active cooling. The gas turbinevane 400 also comprises an airfoil 414 that is air cooled by a source ofair entering the airfoil 414 through the outer arc-shaped platform 408and passing along the walls of the airfoil and then through a pluralityof openings 420 (see FIGS. 3-5).

A common prior art vane assembly configuration includes two parallelmate face surfaces, often times cut along an angle relative to the vaneplatform leading face, as depicted by A in FIG. 9. Depending onmanufacturing and assembly tolerances, a small gap may be presentbetween the adjacent platforms, thereby providing a way for hotcombustion gases to enter the gap region. When this occurs, the hotgases, often upwards of approximately 2000 deg. F. can cause overheatingand erosion to the platform leading edge region. One instance where thisis known to occur, as shown in FIG. 9, is when there is a bow wave BW ofhot gases extending away from the airfoil leading edge region 218A andthe airfoil leading edge 218A is close enough to the vane platform edgeA that because of the bow wave BW high pressure, it can enter the gapbetween adjacent platforms. As shown in FIG. 9, in the vane assembly theBW is shown coming off the leading edge region of each airfoil.

In yet another embodiment of the present invention, a gas turbine vaneassembly is disclosed. The gas turbine vane assembly 500 is shown indetail in FIGS. 2-6. The assembly 500 comprises a first vane assembly200, a second vane assembly 400, and a fastener mechanism 600.

Through an embodiment of the present invention, where the first vaneassembly 200 is secured to the second vane assembly 400 so as to formthe gas turbine vane assembly 500, significant improvements ineliminating injection of the bow wave gases is achieved, resulting inextended component life of the vane assembly 500. Referring back to FIG.2, the gas turbine vane assembly 500 comprises a first vane assembly 200having a first inner platform 202 having a pressure side radial face 204with first portion 204A, second portion 204B, and a relief cut 208 attheir intersection. Inner platform 202 also includes a suction sideradial face 206, which is a generally straight surface. The first vaneassembly 200 also comprises a first outer platform 210 that is spaced aradial distance from the first inner platform 202 and having a pressureside radial face 212 and a suction side radial face 214, where thepressure side radial face 212 has a first portion 212A and a secondportion 212B joined together at their intersection by a relief cut 216.A first airfoil 218 extends between and joins together the first innerplatform 202 and first outer platform 210.

As it can be seen from FIGS. 2, 3, and 5, referring to the first vaneassembly 200, the first portion 204A of the inner arc-shaped platform202 is generally co-planar with the first portion 212A of the outerarc-shaped platform 210. Furthermore, the second portion 204B of theinner arc-shaped platform 202 is also generally co-planar with thesecond portion 212B of the outer arc-shaped platform 210. Referring toFIGS. 3 and 5, a similar co-planar orientation of inner and outerplatform mate face surfaces also exists for the suction side of the vaneassemblies.

The gas turbine vane assembly 500 further comprises a second vaneassembly 400 that is secured to the first vane assembly 200. Referringto FIG. 3, the second vane assembly 400 comprises a second innerplatform 402 having a pressure side radial face 404 and a suction sideradial face 406, where the suction side radial face 406 has a firstportion 406A and a second portion 406B. The second vane assembly 400also comprises a second outer platform 408, which is spaced a radialdistance from the second inner platform 402 and also has a pressure sideradial face 410 and a suction side radial face 412, where the suctionside radial face 412 has a first portion 412A and a second portion 412B.The second vane assembly 400 also includes a second airfoil 414extending between the second inner platform 402 and the second outerplatform 408.

The first vane assembly 200 and second vane assembly 400 is securedtogether by a fastener mechanism proximate the inner and outerplatforms, as shown in FIGS. 2, 4, and 5. An outer fastening mechanism600 includes a first bracket 602 secured to a first vane assembly 200and a second bracket 604 secured to a second vane assembly 400. Thefirst bracket 602 and second bracket 604 are held together by aremovable fastener such as a pin or bolt (not shown). Referring to FIG.3, an inner fastening mechanism 606 is shown and includes brackets 608and 610 Like the outer fastening mechanism 600, the inner fasteningmechanism 606 is also utilizes removable fasteners, such as a pin orbolt (also not shown) for securing the brackets 608 and 610 together.Because of the vane assembly orientation, the outer fastening mechanism600 utilizes three fasteners, where the inner fastening mechanism 606utilizes one fastener.

The vane assembly 500 is oriented such that the suction side radial face214 of the outer platform 210 of the first vane assembly 200 is adjacentto the pressure side radial face 410 of the outer platform 408 of secondvane assembly 400, as shown in FIG. 2. The fastener mechanism 600secures the first vane assembly 200 to the second vane assembly 400 soas to form a sealed interface. Because of the alternate platformconfiguration disclosed above, and the fastening mechanisms 600 and 606,the joint between the platforms is better sealed than the prior artconfigurations and where the joint is not bolted together. For thenon-bolted mateface, a gap exists and seals are used. With the chevronconfiguration disclosed herein, the gap has been moved further away fromany bow wave coming off the airfoil leading edge, such that the hotcombustion gases do not enter the gap between the vane assemblies.

While the embodiments of the present invention improve the sealingbetween adjacent vanes of a vane assembly, any hot combustion gases thatdo leak between the platform surfaces can be minimized through alternatesealing arrangements. A plurality of flexible sheet metal seals (notshown) can be positioned in slots of the inner and outer platforms toprevent the flow of gases or compressed air in between any gaps of theplatforms. More specifically, and as shown in FIGS. 2 and 3, the firstvane assembly 200, includes a series of slots in the platform matefaces, such as slots 220 in the first inner platform 202 and slots 222in the outer platform 210.

Referring to FIG. 7, a chart showing static gap pressure along themateface of the inner diameter platforms is shown. The solid line(without symbols) indicates the pressure of the cooling air under theplatform. The line with the solid data points shows the gap pressure ofthe prior art vane of FIG. 1. As it can be seen from FIG. 7, the priorart vane assembly has a higher gap pressure than the underplatformpressure along part of the platform. This indicates that some of the hotcombustion gases enters the platform gap (as caused by the bow wave andshape of vane platform), thereby causing erosion in the platform. Theshaded data points indicate the gap pressure of the vane assembly 500 ofthe present invention. As it can be seen from FIG. 7, the inner vaneplatform gap pressure is lower than the under platform pressure. In thisembodiment, because the inner vane platform gap pressure is lower thanthe under platform pressure, hot combustion gases do not enter the gapbetween adjacent platforms.

While the present invention corrects an inflow problem along the innerarc-shaped platforms, no significant inflow problem exists at the outerplatform for the prior art configuration, as shown in FIG. 8. However,the outer platform design of the present invention further increases themargin between the underplatform pressure side and the static pressureat the platform gap.

The present invention has been described in relation to particularembodiments, which are intended in all respects to be illustrativerather than restrictive. Alternative embodiments will become apparent tothose of ordinary skill in the art to which the present inventionpertains without departing from its scope.

From the foregoing, it will be seen that this invention is one welladapted to attain all the ends and objects set forth above, togetherwith other advantages which are obvious and inherent to the system andmethod. It will be understood that certain features and sub-combinationsare of utility and may be employed without reference to other featuresand sub-combinations. This is contemplated by and within the scope ofthe claims.

1. A gas turbine vane comprising: an inner arc-shaped platform having apressure side radial face and a suction side radial face where thepressure side radial face comprises a first portion, a second portion,and a relief cut at the intersection of the first portion and the secondportion; an outer arc-shaped platform spaced a distance radially outwardof the inner arc-shaped platform and having a pressure side radial faceand a suction side radial face where the pressure side radial facecomprises a first portion, a second portion, and a relief cut at theintersection of the first portion and the second portion; and, at leastone airfoil extending between the inner arc-shaped platform and theouter arc-shaped platform.
 2. The gas turbine vane of claim 1, whereinthe first portion of the inner arc-shaped platform is generallyco-planar with the first portion of the outer arc-shaped platform andthe second portion of the inner arc-shaped platform is generallyco-planar with the second portion of the outer arc-shaped platform. 3.The gas turbine vane of claim 1, wherein the first portion and thesecond portion of the pressure side radial face of the inner arc-shapedplatform further comprises an inner seal slot.
 4. The gas turbine vaneof claim 1, wherein the first portion and the second portion of thepressure side radial face of the outer arc-shaped platform furthercomprises an outer seal slot.
 5. The gas turbine vane of claim 1 furthercomprising a bond coating and a thermal barrier coating applied to aportion of the inner arc-shaped platform, a portion of the outerarc-shaped platform, and the at least one airfoil.
 6. The gas turbinevane of claim 1, wherein the airfoil is air cooled by a source of airentering the airfoil through the outer arc-shaped platform.
 7. The gasturbine vane of claim 1, wherein the inner arc-shaped platform, theouter arc-shaped platform, and the airfoil are integrally cast.
 8. A gasturbine vane comprising: an inner arc-shaped platform having a pressureside radial face and a suction side radial face where the suction sideradial face comprises a first portion and a second portion; an outerarc-shaped platform spaced a distance radially outward of the innerarc-shaped platform and having a pressure side radial face and a suctionside radial face where the suction side radial face comprises a firstportion and a second portion; and, at least one airfoil extendingbetween the inner arc-shaped platform and the outer arc-shaped platform;9. The gas turbine vane of claim 8, wherein the first portion of theinner arc-shaped platform is generally co-planar with the first portionof the outer arc-shaped platform and the second portion of the innerarc-shaped platform is generally co-planar with the second portion ofthe outer arc-shaped platform.
 10. The gas turbine vane of claim 8,wherein the first portion and the second portion of the suction sideradial face of the inner arc-shaped platform further comprise a sealslot.
 11. The gas turbine vane of claim 8, wherein the first portion andthe second portion of the suction side radial face of the outerarc-shaped platform further comprise a seal slot.
 12. The gas turbinevane of claim 8 further comprising a bond coating and a thermal barriercoating applied to a portion of the inner arc-shaped platform, a portionof the outer arc-shaped platform, and the at least one airfoil.
 13. Thegas turbine vane of claim 8, wherein the airfoil is air cooled by asource of air entering the airfoil through the outer arc-shapedplatform.
 14. The gas turbine vane of claim 8, wherein the innerarc-shaped platform, the outer arc-shaped platform, and the airfoil areintegrally cast.
 15. A gas turbine vane assembly comprising: a firstvane assembly having: a first inner platform having a pressure sideradial face and a suction side radial face, where the pressure sideradial face has a first portion, a second portion, and a relief cut atthe intersection of the first and second portion; a first outer platformspaced a radial distance from the first inner platform and having apressure side radial face and a suction side radial face, where thepressure side radial face has a first portion and a second portion, anda relief cut at the intersection of the first and second portion; and, afirst airfoil extending between the first inner platform and first outerplatform; a second vane assembly having: a second inner platform havinga pressure side radial face and a suction side radial face, where thesuction side radial face has a first portion and a second portion; asecond outer platform spaced a radial distance from the second innerplatform and having a pressure side radial face and a suction sideradial face, where the suction side radial face has a first portion anda second portion; and, a second airfoil extending between the secondinner platform and second outer platform; and, a fastener mechanismpositioned adjacent the first and second outer platforms and the firstand second inner platforms for securing the first vane assembly to thesecond vane assembly.
 16. The gas turbine vane assembly of claim 15,wherein the fastener mechanism comprises a first bracket secured to thefirst vane assembly and a second bracket secured to the second vaneassembly and one or more removable fasteners.
 17. The gas turbine vaneassembly of claim 16, wherein the suction side radial face of the outerplatform of the first vane assembly is secured to the pressure sideradial face of the outer platform of the second vane assembly by thefastener mechanism.
 18. The gas turbine vane assembly of claim 17,wherein the fastener mechanism causes the first vane assembly to contactthe second vane assembly so as to form a sealed interface.
 19. The gasturbine vane assembly of claim 17, wherein the first portion of theinner arc-shaped platform is generally co-planar with the first portionof the outer arc-shaped platform and the second portion of the innerarc-shaped platform is generally co-planar with the second portion ofthe outer arc-shaped platform.
 20. The gas turbine vane assembly ofclaim 15 further comprising a plurality of flexible sheet metal sealspositioned in respective slots of the inner and outer platforms toprovide a seal between adjacent turbine vane assemblies.